This invention generally relates to perfusion catheters and more particularly to steerable perfusion dilatation catheters for use in coronary angioplasty.
In percutaneous transluminal coronary angioplasty, catheters are inserted into the cardiovascular system through the femoral or brachial arteries under local anesthesia. A preshaped guiding catheter is positioned in the coronary artery, and a dilatation catheter having a distensible balloon portion is advanced through this catheter into the branches of the coronary artery until the balloon portion traverses or crosses a stenotic lesion. The balloon portion is then inflated with a fluid to compress the atherosclerosis in a direction generally perpendicular to the wall of the artery, thereby dilating the lumen of the artery.
A guidewire is often employed to facilitate placement of the dilatation catheter beyond the distal end of the guiding catheter The guidewire is inserted through the guiding catheter, and the dilatation catheter is advanced along the guidewire to the desired position in the vascular system.
Since the inflated balloon occludes the flow of blood in the artery or other vessel being treated, the balloon can only be inflated for a limited time, typically on the order of 15-60 seconds. A longer inflation time would be desirable since it would increase the probability that the vessel would remain open after the catheter is removed. With catheters heretofore provided, however, the only way to prolong the inflation is to use repeated short inflations.
Attempts have been made to provide blood flow around the inflated balloon of a dilation catheter during a coronary angioplasty procedure. Examples of these prior art techniques are found in U.S. Pat. Nos. 4,423,725 (Baran et al.) and 4,581,017 (Sahota) and in Ser. No. 903,028, filed Sept. 2, 1986, assigned to the present assignee. Reference is also made to U.S. Pat. No. 4,661,094 also assigned to the present assignee, which discloses a perfusion catheter which does not have an inflatable balloon but does have holes and a flow passage for carrying blood through an obstruction in a blood vessel. The aforesaid references are hereby incorporated herein in their entirety. However, what has been needed and has been heretofore unavailable are steerable dilatation catheters having means to facilitate the flow of blood when the balloon is inflated. The present invention satisfies this need.